As target and sport archery increases in popularity, several shortcomings of the standard archery equipment limit many users and lead to safety concerns for all. In order to improve the experience and safety, improvements to the standard equipment in the areas of transporting and assembling the crossbow, drawing back the bowstring, releasing the bowstring, and preventing dry-fires are needed.
The basic crossbow form, with a stock and transverse limbs, can be bulky and difficult to store and transport. A case for storing and transporting the crossbow may be determined by the shape of the crossbow, and as such may require a considerable amount of storage space, and may be awkward to carry and move from place to place.
A crossbow having fixed limbs and a stock may be stored or transported in a pre-loaded state, with its bowstring strung between the limbs, avoiding the time and effort required for reassembly, but potentially creating safety concerns and/or elevated component wear over time due to the presence of a continuous preload in the bowstring and the limbs. A crossbow having fixed limbs and a stock may alternatively be stored or transported in an unloaded state (e.g., without a bowstring), allowing relaxation of the limbs during periods of non-use and transport, but potentially requiring a great deal of effort to string the crossbow each time the crossbow is retrieved prior to use.
A crossbow may have limbs that are moveable relative to the stock, thereby permitting the limbs to be collapsed for purposes of storage and transport of the crossbow. In such circumstances, a bowstring of the crossbow may be retained, in a slackened state, between the limbs during storage and transport, or removed therefrom and replaced upon retrieval of the crossbow prior to use. A user may begin the process of placing the limbs in a shooting position by rotating the limbs outward from the stock from the collapsed configuration of the crossbow to arrive at the partially reassembled configuration of the crossbow. Each of the limbs can be rotated outward from the stock to a substantial fraction of its total rotational throw relative thereto before the bowstring loses all of its slack and begins to build tension.
A user may continue the process of placing the limbs in a shooting position by rotating the limbs further outward from the stock from the partially reassembled configuration of the crossbow to the fully assembled configuration. It is only with respect to this relatively small remaining portion of the total rotational throw of the limbs relative to the stock that that the total magnitude of force required to be applied to the limbs and the stock truly begin to grow, and grow rapidly. Further complicating this strenuous task is the general requirement that each of the limbs remain both accurately positioned relative to the stock, as well as securely retained therein, at all times during and after final assembly in order to prevent accidents from occurring (e.g., especially while the crossbow is in use during the hunt).
Once the crossbow is properly configured in the regular position, the user may cock the crossbow in preparation for loading and firing a crossbow arrow or bolt via the bowstring. In general, the crossbow must impart a substantial amount of force in order to accurately propel a bolt with respect to any intended target. In order to store in the crossbow the energy needed to imparting such force to the bolt, the user must draw the bowstring back along the stock to a distance extent sufficient to preload or ‘cock’ the crossbow. This task can also be quite strenuous, generally requiring the user to generate a large amount of force.
A user may cock the crossbow via direct manual cocking. For example, a user of sufficient strength may elect simply to hold the stock with one hand, and draw the bowstring backward along the stock to a sufficient distance extent with the other. Alternatively, a user may cock the crossbow via indirect manual cocking. For example, a user may choose to employ an assist device, such as a cord assembly. The cord assembly may include a cord and a pair of manual gripping handles disposed at opposite ends of the cord. Such a user may use their feet to hold a crossbow pointed downward against the ground, couple the cord of the cord assembly to a bowstring of the crossbow, and pull upward as necessary with both hands using the gripping handles. Either way, manual cocking of a crossbow requires a user to generate considerable force, which can quickly become tiring, especially when attempted repeatedly during the course of a hunt.
Various mechanisms have been developed over time to assist the user in generating the force necessary to cock a crossbow. An example of such a mechanism is a crossbow having a stock and a bowstring may further include a crank assembly having a housing, a length of cord, and a rotatable crank arm. A catch is further disposed at an end of the cord. In operation, a user typically manually draws the bowstring far enough toward the housing to permit the bowstring to be engaged by the catch. The rotatable crank arm is typically of sufficient length, and/or is typically associated with a sufficient amount of mechanical advantage, to permit the user to relatively easily reel the cord back into the housing, thereby continuing the process of drawing the bowstring back gradually along the stock, even as the amount of tension in the bowstring begins to grow rapidly. Eventually, the bowstring will have been drawn back along the stock sufficiently to cause the crossbow to become cocked, at which time the cord may be safely detached from the bowstring and fully reeled back into the housing (e.g., for storage in advance of next use). While plainly useful for completing the strenuous final state of drawing back the bowstring, such a crank assembly can add considerable weight and/or bulk to the crossbow.
A cocked crossbow embodies a great deal of stored energy. Such stored energy may be released in different ways. For example, a user can load an arrow or ‘bolt’ onto a cocked crossbow and thereafter actuate an associated trigger mechanism, thus firing the bolt from the crossbow (i.e., energy release via transfer/conversion). For another example, a user may decide not to fire a bolt, but rather to ‘decock’ the crossbow by reversing (e.g., in a safe, controlled fashion) the process by which the crossbow was cocked (i.e., energy release via dissipation). In most if not all instances, however, it will generally be important to prevent the crossbow from releasing such stored energy prematurely, and/or as a result of an accident. For example, while the crossbow is being moved during hunting, but prior to firing, it may be advantageous to keep the crossbow fully cocked (e.g., for purposes of readiness), but unloaded (e.g., for purposes of safety and/or convenience), such that all a user would need to do to fire the crossbow, once the decision to do so is finally made, is to load a bolt onto the crossbow stock, and then actuate an associated trigger mechanism (e.g., by pulling a trigger), allowing the bowstring to move forward and outward of the trigger mechanism, thereby rapidly propelling the bolt away from the crossbow along the same forward direction.
Keeping the trigger mechanism in such an advanced state of readiness can tend to minimize both the total amount of time needed, as well as the total amount of physical effort required to be expended in actually firing the crossbow, once the decision is finally made to do so. Unfortunately, however, the same advanced state of firing readiness in the trigger mechanism can tend to leave the crossbow vulnerable to so-called ‘dry fire’, in which a cocked bowstring of the crossbow is unintentionally released prior to a bolt being loaded in the crossbow, such that the time and effort needed to cock the crossbow in the first place must now be repeated. Dry fire can occur in any number of situations, including, for example, situations in which the crossbow is dropped, or in which the trigger mechanism is mistakenly actuated (e.g., while the crossbow is being moved, stowed, or retrieved during hunting).
In order to protect against dry fire, modern crossbow designs will typically include corresponding safety mechanisms. For example, a crossbow may include a stock, a trigger mechanism, and a stop mechanism. The stop mechanism may include an arm that may be biased (e.g., via spring-loading) toward movement in the counter clockwise direction, but is deflectable as necessary in the opposite rotational direction. The stop mechanism may further include a manually operable handle. During a process of cocking the crossbow, the bowstring is drawn along the stock toward the trigger mechanism. Reaching the position of the stop mechanism, the bowstring will tend, as it passes the arm, to displace the arm upward and away from the rearward directed path of the bowstring along the stock. Upon further drawing of the bowstring into the trigger mechanism and past the position of the stop mechanism to complete cocking of the crossbow, the arm, now no longer in contact with the bowstring, is urged (e.g., via the aforementioned spring load) or otherwise allowed to rotate downward again, such that the arm is caused to rest against the stock.
In firing operation of the crossbow (i.e., after the same has been cocked as described above), the dry fire prevention function (described more fully below) of the stop mechanism is overridden. More particularly, a bolt may be loaded onto the crossbow by being moved backward along the stock along the direction, toward and into the trigger mechanism. In the process of being loaded onto the crossbow, a tail end of the bolt displaces the arm upwards and out of the rearward path of the bolt. At this time, and up until a moment of firing the bolt, the arm may be allowed to rest atop a longitudinal shaft of the bolt. Upon the trigger mechanism being actuated, the bowstring is released. Since the arm of the stop mechanism remains displaced away from a forward path of the bowstring and of the bolt along the direction, the stop mechanism presents no obstruction with respect to continued forward motion of the same.
The crossbow is further operable in a dry fire prevention mode, with respect to which the arm of the stop mechanism, at least initially, tends to rest against the stock of the crossbow. More particularly, after the crossbow has been cocked, but before the crossbow has been loaded with a bolt as described above, the trigger mechanism may be vulnerable to inadvertent actuation, normally leading to an unintended release of the bowstring from the trigger mechanism. Upon the now released bowstring moving forward to the position of the stop mechanism, the arm serves to ‘catch’ the bowstring at a position along the stock just forward of the trigger mechanism. Thereafter, the arm further cooperates with the stock to block any further forward motion of the bowstring. The user is now permitted to recock the bowstring by drawing the bowstring back into engagement with the trigger mechanism, or, alternatively, to allow a full, but now gradual release of the bowstring by a) partially drawing the bowstring back toward the trigger mechanism, b) manually displacing the arm upward and away from the bowstring by pulling downward on the handle, and c) permitting the bowstring to move slowly forward again along the direction.
By limiting unintended discharge of the bowstring to a relatively small throw during dry fire, the stop mechanism provides an important safety feature. However, even when working as intended, the stop mechanism not only still fails to prevent dry fire, but also requires the bowstring to be redrawn to at least some extent backward along the stock and back into engagement with the trigger mechanism to restore the crossbow to the fully cocked state. Accordingly, apparatus and methods for preventing unintended discharge of a trigger mechanism of an unloaded crossbow remain both desirable and necessary.
As discussed above, once a crossbow has been cocked, it may be loaded with a bolt and fired. Referring now to FIGS. 1, 2 and 3, numerous trigger mechanisms have been devised for use in releasing the bowstring of a cocked and loaded crossbow. Referring specifically to FIG. 1, a so-called ‘power-touch’ trigger mechanism 1100 is shown, including a string stop 1102 for engaging and retaining a cocked bowstring 1104, and a trigger 1106. The string stop 1102 includes a forward—(e.g., rightward) facing reaction surface 1108 and the trigger 1106 includes a corresponding rearward—(e.g., leftward) facing reaction surface 1110. Forward-directed pulling force from the bowstring 1104 tends to urge the string stop 1102 in a counter-clockwise direction 1112. However, the trigger 1106 is itself biased toward movement in the counter-clockwise direction, such that prior to actuation of the trigger 1106, the reaction surface 1110 of the trigger 1106 engages (e.g., via surface-to-surface or edge-to-surface contact) the reaction surface 1108 of the string stop 1102, and the forward-directing pulling force from the bowstring 1104 is squarely opposed. A user actuates the trigger 1106 via a rearward-directed pull on a trigger blade 1114, pivoting the trigger 1106 in a clockwise direction 1116, thereby withdrawing the reaction surface 1110 from the reaction surface 1108 and allowing the bowstring 1104 to begin pulling the string stop 1102 in the counter-clockwise direction 1112 such that the latter releases the former.
Referring now to FIG. 2, a so-called ‘drop latch’ trigger mechanism 1200 is shown, including a string stop 1102 for engaging and retaining a cocked bowstring 1204, and a trigger 1206. The string stop 1202 includes a rearward-facing reaction surface 1208 and the trigger 1206 includes a corresponding forward-facing reaction surface 1210. Forward-directed pulling force from the bowstring 1204 tends to urge the string stop 1202 in a clockwise direction 1212. However, the trigger 1206 is biased toward movement in the counter-clockwise direction, such that prior to actuation of the trigger 1206, the reaction surface 1210 of the trigger 1206 engages (e.g., via surface-to-surface or edge-to-surface contact) the reaction surface 1208 of the string stop 1202, and the forward-directing pulling force from the bowstring 1204 is squarely opposed. A user actuates the trigger 1206 via a rearward-directed pull on a trigger blade 1214, pivoting the trigger 1206 in a clockwise direction 1216, thereby withdrawing the reaction surface 1210 from the reaction surface 1208 and allowing the bowstring 1204 to begin rotating the string stop 1202 in the clockwise direction 1212 such that the latter releases the former.
Turning now to FIG. 3, a so-called ‘roller touch’ trigger mechanism 1300 is shown, including a string stop 1302 for engaging and retaining a cocked bowstring 1304, and a trigger 1306. The string stop 1302 includes a rearward-facing reaction surface 1308 and the trigger 1306 includes a roller 1309 exhibiting a rotating reaction surface 1310. Forward-directed pulling force from the bowstring 1304 tends to urge the string stop 1302 in a clockwise direction 1312. However, the trigger 1306 is biased toward movement in the counter-clockwise direction, such that prior to actuation of the trigger 1306, the reaction surface 1310 of the trigger 1306 engages (e.g., via line-to-surface contact) the reaction surface 1308 of the string stop 1302, and the forward-directing pulling force from the bowstring 1304 is squarely opposed. A user actuates the trigger 1306 via a rearward-directed pull on a trigger blade 1314, pivoting the trigger 1306 in a clockwise direction 1316, thereby rolling the roller 1309 across the reaction surface 1308 to a point where the reaction surface 1310 releases the reaction surface 1308, allowing the bowstring 1304 to begin rotating the string stop 1302 in the clockwise direction 1312, rapidly causing the latter to release the former.
As discussed above with respect to FIGS. 1, 2 and 3, each of the trigger mechanisms 1100, 1200 and 1300 includes opposing pairs of reaction surfaces 1108 and 1110, 1208 and 1210, and 1308 and 1310 that are at least temporarily aligned and brought into load-bearing contact with each other as part of the crossbow cocking process. At different times and during different phases of the crossbow cocking and firing process, the bowstring 1104, 1204, 1304 will tend to pull with a considerable amount of force on the string stop 1102, 1202, 1302. Typical trigger mechanism designs, however, including the trigger mechanisms 1100, 1200, 1300 discussed herein, tend to confine actual force-bearing interaction as between such reaction surfaces to a relatively short line (e.g., as in line-to-surface or edge-to-surface contact) or to a relatively small area (e.g., as in surface-to surface contact). While this may beneficially reduce the required rotational throw of the trigger blade 1114, 1214, 1314 to a minimum extent, and perhaps enhance the overall precision of the instrument, such an arrangement unfortunately also tends to result in an elevated contact pressure between the reaction surfaces involved. Unfortunately, at least with respect to the present context, along with such elevated contact pressure between the reaction surfaces typically comes an elevated degree of friction between the string stop 1102, 1202, 1302 and the trigger 1106, 1206, 1306 which a user must manually overcome in order to successfully actuate the trigger mechanism 1100, 1200, 1300. Accordingly, apparatus and methods for limiting or reducing the amount of user-generated force required to actuate a crossbow trigger mechanism are both desirable and necessary.